The field of backrests has been the subject of developmental efforts for many years. This is due largely to the fact that back pain and back disorders afflict a major segment of the population. For a number of reasons such as bad posture, poor sitting habits, or poor physical condition, the natural elongated S-shape of the spinal column may become distorted. A well constructed backrest, properly adjusted, tends to restore the spinal S-curve to proper configuration and thereby relieves or avoids the uneven pressures on discs and vertebrae which cause troublesome pain and fatigue.
The following prior art patents disclose a variety of backrests, some of which are portable and others of which are built into chairs or vehicle seats: U.S. Pat. Nos. 2,756,809--Endresen; 2,843,195--Barvaeus; 2,894,565--Conner; 3,642,319--Berchicci; 3,663,055--Gale; 3,762,769--Poschl; 3,990,742--Glass et al.; 4,350,338--Weiner; 4,239,282--White; 3,890,000--Easley; 4,465,317--Schwartz; and French patent No. 1,182,558--Fader.